:root {
    --bg: #f3f6fb;
    --surface: #ffffff;
    --surface-alt: #f8fbff;
    --text: #0f1b2d;
    --muted: #53627a;
    --primary: #0f6fff;
    --primary-hover: #005be1;
    --border: #d8e1f0;
    --shadow: 0 8px 24px rgba(16, 40, 80, 0.08);
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Inter, Segoe UI, Roboto, Arial, sans-serif;
    background: linear-gradient(180deg, #eef3fa, var(--bg));
    color: var(--text);
    min-height: 100vh;
}

.galton-app {
    width: min(1180px, 96vw);
    margin: 18px auto 26px;
    display: grid;
    gap: 14px;
}

.app-header,
.controls,
.stats,
.board-panel,
.histogram-panel {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.app-header {
    padding: 20px 20px 16px;
}

.app-header h1 {
    margin: 0;
    font-size: clamp(1.35rem, 2.15vw, 1.95rem);
    letter-spacing: -0.01em;
}

.app-header p {
    margin: 7px 0 0;
    color: var(--muted);
}

.controls {
    padding: 14px;
    display: grid;
    grid-template-columns: repeat(4, minmax(160px, 1fr));
    gap: 10px;
    align-items: end;
}

.control-group {
    display: grid;
    gap: 6px;
}

.control-group label {
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--muted);
}

.control-group input,
.control-group select {
    height: 40px;
    border: 1px solid var(--border);
    border-radius: 9px;
    background: var(--surface-alt);
    color: var(--text);
    padding: 0 12px;
    font-size: 0.95rem;
}

.control-group input:focus,
.control-group select:focus,
.btn:focus {
    outline: 2px solid #93bcff;
    outline-offset: 1px;
}

.button-group {
    display: flex;
    gap: 8px;
    justify-content: flex-end;
    flex-wrap: wrap;
}

.btn {
    height: 40px;
    border-radius: 9px;
    border: 1px solid var(--border);
    background: #f6f8fc;
    color: #1b2c47;
    padding: 0 16px;
    font-weight: 600;
    cursor: pointer;
}

.btn:hover {
    background: #edf3ff;
}

.btn-primary {
    background: var(--primary);
    border-color: var(--primary);
    color: #ffffff;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.stats {
    padding: 12px;
    display: grid;
    gap: 10px;
    grid-template-columns: repeat(4, minmax(120px, 1fr));
}

.stats article {
    background: #f8fbff;
    border: 1px solid var(--border);
    border-radius: 9px;
    padding: 10px 12px;
}

.stats span {
    color: var(--muted);
    font-size: 0.85rem;
    display: block;
}

.stats strong {
    display: block;
    margin-top: 4px;
    font-size: 1.2rem;
}

.board-panel,
.histogram-panel {
    padding: 12px;
}

.simulation-container {
    width: 100%;
    min-height: 560px;
    border: 1px solid var(--border);
    border-radius: 9px;
    background: linear-gradient(180deg, #f6f9ff 0%, #deebff 62%, #cddfff 100%);
    overflow: hidden;
}

.histogram-panel h2 {
    margin: 2px 0 8px;
    font-size: 1rem;
    color: var(--muted);
}

#histogramCanvas {
    width: 100%;
    height: 320px;
    display: block;
    background: #f6f9ff;
    border: 1px solid var(--border);
    border-radius: 9px;
}

@media (max-width: 980px) {
    .controls {
        grid-template-columns: repeat(2, minmax(140px, 1fr));
    }

    .stats {
        grid-template-columns: repeat(2, minmax(120px, 1fr));
    }

    .button-group {
        justify-content: flex-start;
    }
}